Knocking noise

[Thunder_Storm]

My car started this a few days ago and it is driving me nuts. It only does it between 2300-3500 rpm, and only when at driving at a steady speed or slowly accelerating. Put a heavy load on it and it stops let out of it and it stops. My experience with a spun rod bearing has always been having major oil pressure issues along with it. My oil pressure gauge stays steady in the middle, the oil pan is full, and the oil is clean. This is my first mod motor car, so I have little experience with them. here's a link to a video of the noise

https://www.youtube.com/watch?v=gvsnsA2UOxU

 

[TBCobra]

Video is private.

When I spun a bearing my oil pressure gauge was fine. Dont always go by that piece of junk.

So your car isnt smoking or anything?
Does is sound like the top or bottom of the motor?
Is it a tick or a knock?

 

[Thunder_Storm]

I fixed the vid so it can be watched. No smoke, it sounds like it's coming from the transmission

 

[ddeem]

Sounds just like my rebuilt motor... I posted Cobra Tapping Under Load a while ago and am still trouble shooting the issue. Replaced timing chains, tensioners, guides. Listen at about 1:20 and you can hear it pretty well. Mine does it around 3K as you ease into the throttle. I am going to replace the lash adjusters next but most people say they are never load dependent. Absolutely no other issues with motor (No metal, smoke, oil pressure issues, no power issues, etc) Just this stupid tick / tap.

Mustang 2001 Cobra Tapping - YouTube

 

[RX1Cobra]

The oil pressure gauge is nothing more than an idiot light. If its got a certain psi it sits in that same spot no matter what the actual pressure is. Hard to tell but you sure it's not an exhaust leak?

 

[Thunder_Storm]

No exhaust leaks I spent a week chasing those down after installing the x pipe. To me it sounds as if it's coming from the middle of the trans. The clutch has just started slipping so I'm praying that that is what it is, but I've never heard a clutch make that type of noise.

 

[quick01snake]

The oil pressure gauge is nothing more than an idiot light. If its got a certain psi it sits in that same spot no matter what the actual pressure is. Hard to tell but you sure it's not an exhaust leak?

X2, that idiot gauge is only good for telling you your oil pressure isn't zero. I think it kicks on at like 5-7 psi

 

[sn94cobra]

Does the noise go away when it warms up?

 

[Thunder_Storm]

Stays the same hot, or cold.

 

[Michaelslilgray]

still sounds like an exhaust leak.. if not from the mid pipe from a primary....

 

[MysticVert]

my 99 did the same thing, it was a rod bearing. oil pressure gauge showed fine.

 

[01rowlandcobra]

Mine been doing pretty much the same exact thing exp mine is between 2k and 2300 for the past 10k on a fresh motor rebuild mine sounds like it's coming from the trans 2 I think it's the throw out bearing

 

[txrunner]

subscribing to this thread. I have the same thing in my 96 cobra. Mine goes away after it warms up some. I always thought that it was my long tube headers rattling against the heat shield. Didn't effect performance at all.

 

[DC97Cobra]

STOP DRIVING IT! Mine made the EXACT same noise at the same RPMS. Like everyone has said, the oil pressure gauge is a joke. I was 4 quarts low and the damn thing never budged.

Drain the oil and look for metal flakes before you go any further. If you have metal flakes, support the engine and drop the k member and oil pan so that you can check the connecting rods and crank. If you are lucky like I was, you will only have material that transferred from the bearing to the crank and the crank is fine.

If the crank shows to have been gouged in any way or the connecting rod bearings are no longer staying put in the connecting rod and cap, you may be in need of an engine rebuild.

If you haven't seen my thread yet about my recent experience, go here... http://www.svtperformance.com/forum...-what-does-cobra-do-when-pcv-valve-fails.html

 

[DC97Cobra]

Sounds just like my rebuilt motor... I posted Cobra Tapping Under Load a while ago and am still trouble shooting the issue. Replaced timing chains, tensioners, guides. Listen at about 1:20 and you can hear it pretty well. Mine does it around 3K as you ease into the throttle. I am going to replace the lash adjusters next but most people say they are never load dependent. Absolutely no other issues with motor (No metal, smoke, oil pressure issues, no power issues, etc) Just this stupid tick / tap.

Mustang 2001 Cobra Tapping - YouTube

Your issue sounds more like spark knock. Did you change the compression of the engine and have the tune adjusted to match?

 

[ddeem]

Don't mean to hijack the thread as I have my own on this issue, but I did change to higher compression. I have been told by others that it could be tune related since it is impacted directly by tip-in throttle input at a specific rpm. I do have a Bama tune but it could be a bad part of the throttle curve with the compression.

The tap on the Op video seems like it is much more consistent thru the rpm range. It does sound like either an exhaust leak or the beginning of a rod knock. I would check the oil and cut open the oil filter. I did this and did not have any metal in the filter which helped eliminate the thought of a rod.

Also, couldn't the Op pull one injector at a time to see if it makes any difference to the noise? It did not for me...

 

[DC97Cobra]

He could start off with cutting the oil filter and also drain the oil into a clean pan and then filter it with a coffee or paint filter when bottling the used oil. Both methods should give him a clue on if there is anything metallic banging away.

I've heard a few people say that bama tunes are not good, especially if your car is modified. For example, a friend of mine that owns an 03 Cobra did a dyno pull with his bama tune only to find it was leaning out a lot. The shop did just a quick adjustment to the tune so that he would not hurt the engine but strongly recommended that he either talk to bama or get the car dyno tuned.

With the rumors and seeing the experience first hand, I would suggest getting the car tuned. It could be tip in on the timing or maybe need a little bit more fuel. Curious... have you tried running a higher octane to see if it goes away? The higher octane may help reduce the detonation and give a little more insight if its running lean or timing is too advanced.

 

[ddeem]

I run 93 octane consistently. I was thinking about dumping in 5 gallons of race fuel on a low tank to see if the sound changes. This would be a fairly cheap test to check if it is detonation...

I have heard similar reports about the bama tunes. Great for bolt ons but as soon as you mention Manly Flat top pistons, they are like "What"? I think it needs more fuel...